Compiler for "Easy" language from "Etudes for Programmers" book (1978)

shrubble 209 days ago |

The Etudes book is considered a classic, especially among FSU programmers-the book was licensed for a small amount, translated into Russian and used in many classrooms.

kragen 209 days ago | |

It's absolutely a classic!

dukoid 209 days ago |

I was assuming it's something similar to PL/0 but the grammar looks quite extensive...

Joker_vD 209 days ago | |

Basically Algol, but with gratuitous "SET" to simplify parsing assignment statements, and without generic "BEGIN" braces: those are baked into "DO"/"THEN"/"ELSE".

You can probably straightforwardly translate it to Golang by running through a C preprocessor with an obvious set of macros.

ape4 209 days ago |

The "FI" for "endif" is like bash.

The semicolons are like C.

The "PROGRAM" section is like COBOL.

kragen 209 days ago | |

The "fi" thing arose during the Algol-68 process, which Steve Bourne participated in, which is why he put it in his shell. (He would have put "od" there too to terminate "do" if it wasn't already used for a hexdumper.) You also find it in, for example, Dijkstra's Discipline of Programming.

Semicolons were widely used as statement separators in Algol-family languages, but in Easy they seem to be statement terminators, so they are apparently like C rather than like earlier Algol-family languages such as Pascal.

Pascal also had the "program" thing. I'm not sure if earlier Algol languages did?

IAmBroom 209 days ago | | |

COBOL precedes Pascal.

kragen 209 days ago | | |

Yes, of course it does. I didn't mean to imply that COBOL got it from Pascal. I meant that the practice was much more widespread than just COBOL, and given that the rest of Easy is clearly an Algol-family language very similar to Pascal or (then-draft) Ada, that's probably where he got it.

Rendello 209 days ago | |

If you're Stephen R. Bourne, "FI" is also like C!

(From the Bourne Shell source): https://www.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/sh...